Voltmeter, suitable for medium/high-voltage devices, having a surface-wave device.
The present invention relates to a voltmeter which is suitable for medium/high-voltage devices.
Many embodiments of high-voltage meters, based on various operating principles, are known. Many such meters operate on a magnetic principle, or with evaluation of the magnetic field of currents flowing in high-voltage devices. For all such devices, a problem to be observed or solved is that of ensuring sufficient high-voltage insulation and to rule out the high-voltage risks to operating personnel and the like which may occur with such meters.
High-voltage meters are, for example, disclosed in the U.S. Pat. Nos. 3,428,896, 3,633,191, 4,158,810 and 4,261,818 as well as in European reference EP-0 314 850 B1. In particular, the latter publication explains the problems which arise in conjunction with multi-conductor high-voltage systems such as three-phase high-voltage lines. This publication describes in detail relatively inexpensive measures by which effects on measurement values, due to the presence of neighbouring high-voltage conductors, can be solved or by which corrections may be made to measured values. This publication also sets out general facts relating to high-voltage meters, which need not therefore be repeated in the description of the present invention.
A decade ago, U.S. Pat. No. 4,611,207 disclosed the features of the precharacterizing clause of Patent a capacitive voltage divider which consists of two capacitors with, arranged between them, an electrically conductive surface element forming a potential surface of the voltage divider, and lies between the high-voltage electrical conductor and a base potential. Associated with these features, this document describes an electronic circuit as a voltmeter device with an amplifier stage and a downstream transmitter stage which necessarily require a power source for supplying them and, like the voltmeter device, are at high-voltage potential.
In a different context, actually a decade ago as well, European reference EP-AUS-0166065A1 and U.S. Pat. No. 4,510,443 disclosed mutually corresponding surface-wave voltmeter devices as described in more detail below.